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ANTENTOP- 03- 2003, # 004

Vacuum Tubes


electrodes. And in 1940 a new project of marking of radio valves was worked out , which eliminated this drawback. The most parameters of the system were close to the international one. The first figure approximately showed the heating voltage, the letter in the second place described the basic purpose of the valve or its construction. The figure in the third place did not have a special meaning and then served for division of the valves of the same purpose and construction. For description of the valves' outer design (except the usual metallic ones) another letter was added: "C" - a glass valve of usual size, "M" - glass, mini-sized, "J" - glass, of "acorn" type, etc.



Soviet mini-sized valves of the battery series. 2V direct heating, an octal base. Early 1940's. The outer conducting coating serves as a screen. Photo shows valves 2G2M, SO-243, 2K2M, SB-243. See "Rodina-47".
The European valves with a "spider" base. 4V indirect heating. End 1930's. Photo shows valves: AK2, AL4, AF3, ABC1, AZ1 made by the "Valvo" and "Telefunken.". It is interesting to note the screening caps used for such valves ("Tefag" chassis).


The radiotrones made by the American "RCA" corporation. Most of them had 6,3V indirect heating. Produced in 1930's. Photo shows tubes: 6A7, 75, 80, 6D6 from "RCA Victor 5T4" receiver. The valve 7G12S of a similar design was produced in the USSR.



In accordance with the new marking system some valves (in particular, the glass mini-sized ones worked out in 1938) got a new marking. For instance, the valve model SB-242 should be marked 2A1M, the SO-241 - as 2K1M etc. But the new marking was not generally accepted because the radio works continued production of valves with the old marking. Only mini-sized valves of a later design (2K2M, 2J2M) were marked in a new way.


Because by the time there were still many radios in operation using valves of the old 4-Volt glass series our industry produced for some time valves substituting the former types. The names of substituting valves are the following: 4N4S (for SO-118), 4F5S (for SO-122), 4J5S (for SO-124). The inner framework of the tubes

The valves with a T-type base (8 pins). Left - the metallic valve EF14 made by "Telefunken G.m.b.H." for military purposes (WWII) with the inscription "Wehrmacht". Then follow the UCL11, EYY13 and the vacuum impulses counter N3 made by the "Dressler"

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